According to the contents of the waiter's working rules, first of all, you should bend your index finger and tap the door three times to identify yourself: hello, waiter. Knock three times in a row. If there is no response, you can open the door and go in. But when you enter, you should open the door halfway and scan the room through the crack of the door to see if there is anyone. If there is someone, you should apologize and leave the room immediately and lock the door.

When you don't know if there is anyone in the room, knocking at the door is the most basic step, which is not only out of courtesy, but also out of respect for the privacy of the guests. Because customers are disgusted that their rooms are randomly entered by irrelevant people, this will make them feel insecure and may lead to a series of problems, such as complaints and scolding.

I hope my answer can help you!